<!DOCTYPE html>
<html>
    <head>
	<title>定位层级</title>
	<meta charset="UTF-8">
	<style>
	    body div:first-child{
		width: 500px;
		height: 500px;
		background: red;
		color: #fff;
		position: fixed;
		top: 0;
		left: 0;
		z-index: 2;
	    }
	    body div:last-child{
		width: 300px;
		height: 300px;
		background: #66ff66;
		position: fixed;
		top: 0;
		left: 0;
		z-index: 1;
	    }
	</style>
    </head>
    <body>
	
	
	<div>1111111111111111111</div>
	<div>2222222222222222222</div>
	
    </body>
</html>
